1. Field of Invention
The present invention relates to a wear-resistant aluminum-alloy which is appropriate for weight-reduction of sliding parts. The present invention also relates to a method for working the wear-resistant aluminum-alloy.
2. Description of Related Arts
Wear-resistant aluminum-alloys are used for such sliding members, whose light weight is of importance, in a application such as the vane and the rotor of a rotary compressor, the valve-operating system of an internal combustion engine, a cylinder of a magnetic head, the cylinder of a miniature engine used for a model, and the piston of an engine. The wear-resistant aluminum-alloys are used in combination with cast iron or alloyed steel, which is the material of the opposed sliding member. The required properties of these materials are wear-resistance along with excellent strength and heat-resistance. In addition, the difference in the coefficient of thermal expansion of the opposed and sliding members should be minimal.
Al-Si alloy is well known as an aluminum alloy having excellent wear-resistance. Particularly, Al-Si alloy having Si content of from 12 to 25% by weight is used extensively. The Al-Si alloy mostly used is a cast material. In order to utilize the wear-resistance property of primary Si, coarse Si crystals, of 20 .mu.m or more in size are formed in the cast Al-Si alloy.
The coarse primary Si of the cast Al-Si alloy increases, however, the wear of the opposed material. The strength of this Al-Si alloy is low, because it is cast material. Furthermore, any form of machining, cold working or warm working, is impossible for such alloy because the coarse primary Si is dispersed in the cast aluminum alloy. When the Si content is decreased to improve the workability, the coefficient of thermal expansion increases, thus creating a problem with regard to clearance between the sliding and opposed members.